共查询到3条相似文献，搜索用时 0 毫秒
1.
This paper shows that there exists a mechanism of longitudinal plasma acceleration which is inherent in the process of the
process of resonant conversion of a fast magnetosonic wave freely propagating along the magnetic field into an Alfvén wave.
This mechanism is caused by the Ampere force arising due to the interaction between the poloidal component of the current
of the compressible disturbance and the generated toroidal disturbance. It is shown that plasma acceleration takes place at
the stage of increase in the Alfvén wave amplitude and that the accelerated flow retains its velocity when the process of
resonant conversion is over. We describe spatiotemporal structures of plasma flows arising with the transformation of fast
magnetosonic waves into Alfvén waves. An interpretation of the presence of fast ion flows in the magnetotail as a consequence
of the action of the plasma acceleration mechanism considered in this work is proposed. 相似文献
2.
DongXiao Pan WeiJie Sun QuanQi Shi AnMin Tian ZhongHua Yao SuiYan Fu QiuGang Zong XuZhi Zhou ZuYin Pu 《中国科学:地球科学(英文版)》2016,59(3):548-555
Using Time History of Events and Macroscale Interactions during Substorms(THEMIS) observations from 2007 to 2011 tail seasons, we study the plasma properties of high speed flows(HSFs) and background plasma sheet events(BPSs) in Earth's magnetotail(|Y_(GSM)|13R_E, |Z_(GSM)|5R_E, –30R_EX_(GSM)–6R_E), and their correlations with solar wind parameters. Statistical results show that the closer the HSFs and BPSs are to the Earth, the hotter they become, and the temperature increase of HSFs is larger than that of BPSs. The density and temperature ratios between HSFs and BPSs are also larger when events are closer to Earth. We also find that the best correlations between the HSFs(BPSs) density and the solar wind density occur when the solar wind density is averaged 2(3.5) hours prior to the onset of HSFs(BPSs). The normalized densities of both HSFs and BPSs are correlated with the interplanetary magnetic field(IMF) θ angles(θ=arctan(B_Z/((B_x~2)+(B_y~2))~(1/2) which are averaged 3 hours before the observation time. Further analysis indicates that both HSFs and BPSs become denser during the northward IMF period. 相似文献
3.
The results of studying the intensity of fluxes of 30–80 keV ions from the data of measurements of the NOAA (POES) sun-synchronous satellites during geomagnetic storms of different intensity are presented. For 15 geomagnetic storms with |Dst|max from ~37 to ~422 nT, the storm-time maximum ion fluxes in the near-equatorial region (trapped particles) and at high latitudes (precipitating particles) have been considered. It is shown that the maximum fluxes of trapped particles, which are considered a ring-current proxy, increase with the storm power. In this case, if a smooth growth of fluxes is recorded for storms with |Dst|max < 250 nT in the near-equatorial region, a significantly steeper growth of fluxes of trapped particles is observed when storm power increases during storms with |Dst|max > 250 nT. This may be evidence of both an increasing of the contribution of the ring current relative to magnetotail currents to the development of high-intensity storms and to a nonlinear link between the ring current and ion fluxes at low altitudes in the near-equatorial region. Despite large variations in fluxes of precipitating particles in the polar region above the boundary of isotropization, a decreasing tendency, as a whole, in fluxes of these particles is observed with increasing the storm intensity. This is the evidence of the effect of saturation of magnetotail currents and of an increase in the relative role of the ring current during strong magnetic storms. 相似文献